By using an inert atmosphere for processing, totally flux-less soldering is theoretically possible. However, all the components (including the PCB) will need to be oxide-free and have excellent solderability. Because at least some components on the average assembly are likely to have poor solderability, a flux will almost certainly be needed.
Understandably, dispensing entirely with flux is attractive, and the alternative of plasma cleaning has been shown to allow truly flux-less wave soldering in some applications, although at the expense of equipment complexity. However, for reflow soldering, at least some organic materials are needed in order to create a printable, tacky paste.
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